The world is full of stop-gap technologies, because switching is hard and expensive. I have a PNG of my signature and a PDF-to-fax service, because I sometimes need to interface with legacy systems. I still have a checkbook, which I use once or twice a year. I have a full set of metric and SAE wrenches. Hell, I've still got some RS-232 cables.

Duplex is an adapter, a shim, an abstraction layer. It's not perfect, but it solves a problem.